[Finite element analysis of impact of bone mass and volume in low-density zone beneath tibial plateau on cartilage and meniscus in knee joint]

Abstract

Objective: To investigate the impact of bone mass and volume of low-density zones beneath the tibial plateau on the maximum von Mises stresses experienced by the cartilage and meniscus in the knee joint.

Methods: The study included one healthy adult volunteer, from whom CT scans were obtained, and one patient diagnosed with knee osteoarthrisis (KOA), for whom X-ray films were acquired. A static model of the knee joint featuring a low-density zone was established based on a normal knee model. In the finite element analysis, axial loads of 1 000 N and 1 800 N were applied to the weight-bearing region of the upper surface of the femoral head for model validation and subsequent finite element studies, respectively. The maximum von Mises stresses in the femoral cartilage, as well as the medial and lateral tibial cartilage and menisci, were observed, and the stress percentage of the medial and lateral components were concurrently analyzed. Additionally, HE staining, as well as alkaline magenta staining, were performed on the pathological specimens of patients with KOA in various low-density regions.

Results: The results of model validation indicated that the model was consistent with normal anatomical structures and correlated with previous calculations documented in the literature. Static analysis revealed that the maximum von Mises stress in the medial component of the normal knee was the lowest and increased with the advancement of the hypointensity zone. In contrast, the lateral component exhibited an opposing trend, with the maximum von Mises stress in the lateral component being the highest and decreasing as the hypointensity zone progressed. Additionally, the medial component experienced an increasing proportion of stress within the overall knee joint. HE staining demonstrated that the chondrocyte layer progressively deteriorated and may even disappear as the hypointensity zone expanded. Furthermore, alkaline magenta staining indicated that the severity of microfractures in the trabecular bone increased concurrently with the expansion of the hypointensity zone.

Conclusion: The presence of subtalar plateau low-density zone may aggravate joint degeneration. In clinical practice, it is necessary to pay attention to the changes in the subtalar plateau low-density zone and actively take effective measures to strengthen the bone status of the subtalar plateau low-density zone and restore the complete biomechanical function of the knee joint, in order to slow down or reverse the progression of osteoarthritis.

Keywords: Osteoarthritis; cartilage; finite element analysis; low-density zone; meniscus.

图 1

Model matching and validation 模型匹配与验证

图 2

Construction and alignment of the low-density zone model 低密度区模型的构建及配准

图 3

Convergence analysis results of mesh 网格收敛分析结果

图 4

Effect of different degrees of bone loss on the distribution of soft tissue stresses within the knee joint 骨量减少不同程度对膝关节内软组织应力分配的影响

图 5

Comparison of soft tissue stress distribution within the knee joint in groups with different degrees of bone loss 骨量减少不同程度组膝关节内软组织应力分配比较

图 6

Influence of different volumetric low-density zones on stress distribution in soft tissues within the knee joint 不同体积低密度区对膝关节内软组织应力分配的影响

图 7

Comparison of soft tissue stress distribution within the knee joint in different volume low-density zone groups 不同体积低密度区组膝关节内软组织应力分配比较

图 8

HE staining of medial tibial plateau cartilage with different grades low-density zone 不同等级低密度区内侧胫骨平台软骨HE染色

图 9

Alkaline magenta staining of medial tibial plateau cartilage and subchondral cancellous bone with different grades low density zone 不同等级低密度区内侧胫骨平台软骨及软骨下松质骨碱性品红染色